1. Field of the Invention
The present invention relates in general to the field of displaying information, and more particularly to a method and system for control of display lamp illumination with lens cap position.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
One increasingly common way of displaying information is to communicate the information to a portable projector and project an image on a large screen using a bright display lamp. Portable projectors increase the convenience of display of computer generated information, such as presentations generated by Power Point or other applications running on portable information handling systems, by allowing the direct display of information from an information handling system instead of outputting display slide shows or overhead slides. Projector displays have steadily improved in quality with higher lumen output lamps for increased brightness and clarity of displayed information. Further, portable projectors have decreased in size and cost so that traveling business people are more easily able to carry and use projectors for presenting information on screens viewable by large audiences.
One difficulty with portable projectors is that the high lumen bright lamps typically used by portable projectors output considerable heat and, as the brightness output by projectors increases, so does the heat. In normal operations, the lamp is cooled, such as with a cooling airflow, to remove excess heat. However, projector users, who are often under intense pressure when performing presentations, sometimes incorrectly use the projector by inserting the lens cap over the projector lens to block light instead of simply turning off the lamp. Under the intense light of a high lumen lamp, lens caps will melt in a relatively short time period, perhaps leading to destruction of the projector or injury to the user and even creating a fire hazard. One solution is to use a clear or translucent lens cap that does not absorb heat as quickly. However, such lens caps will generally melt eventually and users seeking to block light during a presentation may instead place a different device over the lens to block light, even a flammable device, thus creating an increased danger. Another solution is to use a non-melting material, such as metal or high temperature plastic resins. However, metal lens caps become excessively hot resulting in a risk of burn injury to the user and high temperature resins are difficult to make and mold into parts. Another solution is to display less bright colors at the lens cap when an idle screen is displayed, however, the displayed information generally depends upon the selection of the user who may be attempting to block a bright display temporarily during a presentation.
Therefore a need has arisen for a method and system which controls display lamp illumination of a portable projector based on lens cap position.
In accordance with the present invention, a method and system are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for preventing melting of lens caps that are placed over a lens illuminating light from a lamp. An auto-sensing lens cap detects blocking of illumination by the presence of the lens cap proximate the lens and reduces illumination from the lamp to prevent damage to the lens cap.
More specifically, a lens cap position sensor detects when the lens cap is placed over a lens. For instance, electrical contacts integrated in the lens cap complete a circuit with a conductive portion of the lens housing to signal that the lens cap is inserted over the lens. Alternatively, a light sensor or heat sensor located on the inner surface of the lens cap detects light or heat generated by illumination from the lamp on the sensor when the lens cap is blocking the lamp. The lens cap position sensor signals that the lens cap is positioned proximate the lens through wires that secure the lens cap to the projector. The lens cap position sensor signal is provided to an illumination controller that reduces illumination of the lamp to prevent melting or otherwise overheating the lens cap. For instance, firmware of the projector turns off the lamp after a predetermined time in which the lens cap covers the lens. Alternatively, the processor of the projector reduces illumination by overriding the current display of information with a dark display. When the lens cap position sensor detects removal of the lens cap from blocking the lens, the illumination controller resumes display of information by illumination of the lamp.
The present invention provides a number of important technical advantages. One example of an important technical advantage is that a projector display lamp illumination is controlled based on lens cap position so that illumination is ended or limited when the lens cap is placed over the lens. Reducing or eliminating illumination from a lamp onto a lens cap reduces the risk of melting or burning the lens cap, and thus reduces the risk of injury to the user or damage to the projector. A timed delay from the covering of the lens with the lens cap to the eliminating of lamp illumination reduces interference with a user""s presentation of information that involves limited blocking of projected light. A display of dark colors to limit heat output by the lamp onto the lens cap further reduces impact by allowing recovery of a lamp to full illumination in reduced time relative to the time generally required to initiate illumination from a lamp that is shut off.